Coupling for drill string

ABSTRACT

This dual engaging coupling connects equal segmental lengths of tubing in repeating sequence to form an integrated drill string that is suspended by a thrust bearing means from an immersed buoyant pontoon controlled to regulate the bearing pressure of the lower terminally connected bit upon the bottom of a hole being drilled in subaqueous strata. The primary engagement transmits torque, tension and fluid flow between adjacent ends of the two rigid members. The secondary engagement provides uninterrupted translation of the string through the torque imparting means and power transmission by said repeating sequence whereby a subsequent coupling becomes engaged prior to disengagement of a descending coupling departing from the torquing means. The coupling is adapted to rapid assembly and non-selective of mating ends to preserve axial alignment of the secondary engagement.

United States Patent Nelson 1 June 6, 1972 [54] COUPLING FOR DRILL STRING Primary Examiner-Edward G. Favors [72] Inventor: Arthur John Nelson, 3304 Shasta Drive, 57 AB TRq T San Mateo, Calif. 94403 1 S C t This dual engaging coupling connects equal segmental lengths [.22] 1970 of tubing in repeating sequence to form an integrated drill [21] APPL 85904 string that is suspended by a thrust bearing means from an immersed buoyant pontoon controlled to regulate the bearing pressure of the lower terminally connected bit upon the hot- [52] US. Cl 64/215, 175/6 tom of a hole being drilled in subaqueous strata. The primary [51] Int. Cl ..F16d 3/06 engagement transmits torque, tension and fluid flow between [58] Field of Search ..64/23.5; l75/6 adjacent ends of the two rigid members. The secondary engagement provides uninterrupted translation of the string 5 References (jig d throughthe torque imparting means and power transmission UNITED STATES PATENTS by said repeating sequence whereby a subsequent coupling becomes engaged prior to disengagement of a descending coupling departing from the torquing means. The coupling is adapted to rapid assembly and non-selective of mating ends to preserve axial alignment of the secondary engagement.

COUPLING FOR 1mm. STRING BACKGROUND OF THE INVENTION Conventional drill strings are encased in conductor pipes extending to the drilling station where torque is applied by an intermittently connected Kelly Bar interposed between the drill string and draw works. The extent of travel of the draw works determines the effective length of Kelly Bar providing uninterrupted drilling. Following such penetration the string is retracted, rotation stopped until a new string segment can be interposed between the string and Kelly Bar and thereafter resume drilling.

Thus for every 1000 feet of hole dug, drilling is interrupted some 20 times which entails utilization of all the attending apparatus and disruption to fluid flow of entrained cuttings up the conductor pipe. Furthermore, the lengthened string extending from the drill station in reach to the floor then to the hole bottom in the strata depends upon localized intensity of stress at the very top end of the string, including tension load due to weight of entire string, full torque stress transmitted through the entire string length and maximum net bursting pressure due to the fluid being transmitted to the bit.

The present invention is expressly concerned with the coupling connecting the multiplicity of tubular rigid members comprising a drill string wherein the drill string is suspended from an immersed buoyant station that descends to the drilling station situated below on the strata floor.

Accordingly, it is a purpose of the present invention to pro vide a dual engaging coupling that has: as a primary engagement the connection of two rigid tubular members to transmit torque, tension and fluid flow therebetween; and, as a secondary engagement, to utilize the couplings as the torque transfer means from the drilling station to the drill string.

Still another object is to adapt the couplings for automatic and continuous said transfer of power.

Another object is to produce mating members for unselected assembly.

Yet another object is to facilitate assembly and disassembly of the string segments.

The foregoing and other objects of the invention will become more apparent when viewed in light of the following description and accompanying drawing.

SUMMARY OF THE INVENTION The spline type mating coupling halves are retained in assembled form by the tension existing between the connected rigid members. A snap ring locks the two halves together as the shear member that is spring loaded to disengage upon removal of a fillet spreading the ring to an expanded form in a retaining groove. The coupling has a pair of keyw'ays formed to transmit torque to the extended drill string adapted to pass through the powered drilling station for prolonged uninterrupted penetration of the floor of a body of water. The snap ring lock is relied on to facilitate changes to the drill string and the spline and keyway orientation permits unselected assembly of tubular string segments.

BRIEF DESCRIPTION OF DRAWINGS FIG. 4a is a plan sectional view taken on the plane designated 44 of FIG. 5a.

FIG. 5a is an elevational sectional view connecting two rigid members taken on the plane designated 5--5 of FIG. 4a.

FIG. 5b shows sequential positioning of coupling parts prior to the assembly of FIG. 5a.

FIG. 50 is a plan of the formed spring locking ring.

FIG. 5d details preparation of a portion of the locking ring prior to being deformed.

LEGEND Patent Date Reference application Filed Applicant A 789,494 l-7-69 Arthur J. Nelson B 637,507 8-13-70 Arthur J. Nelson DESCRIPTION (In FIG. 5a) An extended tubular member 541 has a collar 542 formed to the upper end and a plug 543 formed to the lower end to comprise a string segment 146a. Any other plug 543 is engageable within collar 542 of an adjacent segment in torque transmitting relationship by a pair of diametrically opposite jaw projections 544 formed to the exterior of plug 543 receivable in a corresponding recess 545 in collar 542 that had been formed by inwardly projecting jaws 546 within the collar 542 likewise receivable in corresponding recesses 547 in plug 543.

(In FIG. 4a) The abutting shoulders 548 are shown optionally as being equal angularly oriented in torque transmitting relationship of projections 544 and 546.

Snap lock ring 549 engaged in annular groove 550 toencir cle cylindrical portion of plug 543 and bears to the horizontal portional circumferential shoulder 544k to transmit as shear stress in ring 549 the weight of string segments below the ring to the next upper coupling by way of tension in interconnecting member 541. To diminish this shear stress and bearing to ring 549 the shoulder 54412 is made greater than the residual of the circumference represented by shoulder 546h, i.e. shoulders 548 are not then equal angularly spaced though still retaining the diametrically opposite concept so that all couplingsare interchangeable with halves in any 180 oriented arrangement.

A pair of keyways 280 diametrically opposite are formed'in the exterior surface of collar 542 parallel to the longitudinal axis of the string segments with all such keyways of the string in alignment. This drill string therefore is made acceptable to the torque tube 170 of Ref. A wherein at least one coupling is in engagement with the key 278 of that torquing means and the string is torque stressed only by the length extending below the engaged coupling, discounting the minute fluid frictional drag to the string above that coupling.

0' ring gasket 551 positioned in groove 552 formed in plug 543 provides fluid seal with centering sleeve 553 formed in collar 543 for sliding engagement to-plug 543. A pliable seal 554 moulds to the inner surfaces urged by retainer 555 secured by snap ring 556 positioned by groove 557 formedin fingers 558 extending from collar 542 to seal off the top end of the coupling against entry of contaminating materials.

An annular groove 560 formed in collar 542 furthermore adapts this coupling to the shuttle mechanism of Ref. A wherein as there disclosed snap ring 408 positioned in cylinder 392 becomes latched to coupling 148a of the present application. Likewise pin 412 of Ref. A becomes engaged to keyway 280 identical for all couplings; so that this coupling 148a transmits torque, tension loads, fluid flow in uninterrupted fashion to the drill string as powered by the drilling station 150 of Ref. A for continuous penetration as covered in the summary of the present application.

(In FIG. 50) Shown in solid line is the form of ring 549 as would be when seated in groove 550 having a gap 561 resulting from expansion of the ring with a circumferential length less than a full circumference when in a free formed diameter represented in phantom 549a. A fillet 562 is formed to occupy gap 561 as to be subsequently disclosed in assembly of the coupling.

(In FIG. 5d) As part of preliminary preparation of material prior to deforming the ring, a number of slots 563 cut part way through best seen in FIG. 5c leaves solid metal of sufficient body to effect the spring characteristic of the deformed metal; so as to seek a free form of less diameter than the expanded diameter when positioned in groove 550.

ASSEMBLY (In FIG. 5b) This coupling 148a is preferably assembled utilizing a clamp 77 as per Ref. B. As disclosed in that reference the clamp would support the weight of string suspended below the gripped coupling and the single string segment 1460 would rest with plug 543 bearing to collar 542 closing 05 gap 572. The resulting displacement dislocates the lug 543 to the extent that tubular member 541 of lesser diameter now is coincident with groove 550 permitting space toalign free form ring 549a to groove 550. Any suitable tool (tong) is used to expand the ring to seat in the groove whereupon fillet 562 is inserted to fill gap 561 so that the selected tool can be removed then needless to hold the ring seated in the groove. Thereafter pliable seal 554 is butted to ring 549 to be deformed by retainer 555 seated in position by snap ring 556.

When the uppermost string segment I460 is connected as per Ref. B to hoist 83 the transfer of weight ofi clamp 77 will return plug 543 to bear with ring 549 and thereafter clamp 77 v is temporarily expanded to permit lowering of the string for interception of the newly added collar 542. To disassemble the coupling a reversal of the method introduces the need of slots 564 provided in fillet 562 into which a prying tool is inserted to dislodge the fillet whereupon the ring 549 seeks release from groove 550 when the upper string segment 146a rests upon the collar 542 again supported by said clamp 77.

CONCLUSION From the foregoing description it is believed apparent that the present invention enables the accomplishment of the object initially set forth herein. It is understood, however, that the invention is not intended to be limited to the specific details of the exemplary embodiment herein described. No attempt will here be made to enumerate all possible variations or include various incidental elements. It seems apparent that the extent of the present application justified treating it as a supplementary application, deferring claims with this full disclosure of previous concepts then necessarily included in briefest form to fulfill the purpose.

What is claimed is:

' 1. In a drill string exposed to natural environmental conditions in reach from an immersed drilling station established on the floor of a body of water to an immersed buoyant support means above from which the string suspends and said string retained as an integral assembled length established when said support means is in vicinity of the water surface with the drill bit below said station, the improvement comprising:

a. a coupling having mating halves and connecting adjacent ends of a multiplicity of rigid tubular members with equal space sequence measurably less than the length of the torque imparting tube of the drilling station that accommodates uninterrupted passage of the string through the tube with descent of the support means to the station;

b. torque transfer means formed to the couplings continu ously transmitting power from the drilling station to the drill string depending depending upon successive couplings to become in torque transfer engagement with said tube prior to exit from the tube of an adjacent coupling;

a spline type engagement of the mating coupling halves fonned to the ends of each tubular member providing unselected assembly of members to procure integrity of longitudinal alignment of all said torque transfer means of the integral string length;

snap type ring means locking the said halves together for the couplings to transmit as tension to the connected upper member the weight of the string portion below the coupling; and,

sealing means protecting coupling inner parts and sustaining fluid flow between connected rigid members.

2. As in claim 1 the mating coupling halves further comprises:

a. an enlarged end portion of the tubular member having a pair of diametrically opposite identically shouldered protrusions; and,

b. a collar encasing the enlarged end portions of the tubular member having a pair of diametrically opposite cooperating recesses accommodating said protrusions in sliding contact with said shoulders.

3. As in claim 2, the assembled coupling halves further comsin internal annular groove formed in said collar coincident to a hub formed in said enlarged portion accommodating said snap ring providing shoulders resisting withdrawal of the mating coupling halves when subjected to to the load of the suspending string;

b. an accommodating chamber pemtitting displacement of the mating halves for compacting said assembled relationship when the contiguous upper said tubular member is supported from its lower end;

c. said hub is displaced by the diametrically smaller said tubular member upon said compacting of the mating halves; and,

d. said snap ring seeking configuration clear of said annular groove when unrestrained with said hub displaced then fitting to the tubular member permitting separation of the coupling halves. 

1. In a drill string exposed to natural environmental conditions in reach from an immersed drilling station established on the floor of a body of water to an immersed buoyant support means above from which the string suspends and said string retained as an integral assembled length established when said support means is in vicinity of the water surface with the drill bit below said station, the improvement comprising: a. a coupling having mating halves and connecting adjacent ends of a multiplicity of rigid tubular members with equal space sequence measurably less than the length of the torque imparting tube of the drilling station that accommodates uninterrupted passage of the string through the tube with descent of the support means to the station; b. torque transfer means formed to the couplings continuously transmitting power from the drilling station to thE drill string depending depending upon successive couplings to become in torque transfer engagement with said tube prior to exit from the tube of an adjacent coupling; c. a spline type engagement of the mating coupling halves formed to the ends of each tubular member providing unselected assembly of members to procure integrity of longitudinal alignment of all said torque transfer means of the integral string length; d. snap type ring means locking the said halves together for the couplings to transmit as tension to the connected upper member the weight of the string portion below the coupling; and, e. sealing means protecting coupling inner parts and sustaining fluid flow between connected rigid members.
 2. As in claim 1, the mating coupling halves further comprises: a. an enlarged end portion of the tubular member having a pair of diametrically opposite identically shouldered protrusions; and, b. a collar encasing the enlarged end portions of the tubular member having a pair of diametrically opposite cooperating recesses accommodating said protrusions in sliding contact with said shoulders.
 3. As in claim 2, the assembled coupling halves further comprises: a. an internal annular groove formed in said collar coincident to a hub formed in said enlarged portion accommodating said snap ring providing shoulders resisting withdrawal of the mating coupling halves when subjected to to the load of the suspending string; b. an accommodating chamber permitting displacement of the mating halves for compacting said assembled relationship when the contiguous upper said tubular member is supported from its lower end; c. said hub is displaced by the diametrically smaller said tubular member upon said compacting of the mating halves; and, d. said snap ring seeking configuration clear of said annular groove when unrestrained with said hub displaced then fitting to the tubular member permitting separation of the coupling halves. 